Vertical blind



FIG. 1 is a front view of a slat of a vertical blind of this invention;

FIG. 2 is a top view thereof; a bottom view thereof is a mirror image of the view shown in FIG. 2;

FIG. 3 is a left-side view thereof; a right-side view thereof is a mirror image of the view shown in FIG. 3; and,

FIG. 4 is a rear view thereof.

The broken lines form no part of the claimed design. 

The ornamental design for a vertical blind, as shown and described. 